A water shortage protection circuit applied to a water dispenser

Abstract

The utility model discloses a kind of water shortage protection circuit applied to water dispenser, including water flow sensor and heating element power control switch, the water flow sensor is electrically connected with signal conditioning circuit, signal conditioning circuit is electrically connected with water level detection electrode and logic judging module, logic judging module is electrically connected with relay driver, and relay driver is electrically connected with heating element power control switch;The logic judging module includes voltage conversion integration circuit and double signal judging circuit.The utility model judges the mode of water flow state and current condition simultaneously monitoring, only when two conditions are satisfied simultaneously, power supply can be disconnected, effectively reduce the risk of misjudgment trigger, meet use demand.

Description

Technical Field

[0001] This utility model relates to the field of water dispenser technology, and in particular to a water shortage protection circuit for water dispensers. Background Technology

[0002] Traditional water dispensers use hot water coils for heating, which is slow. If the heated water isn't used promptly, it cools down and is repeatedly reheated, creating so-called "repeatedly boiled water," which is unhealthy. Furthermore, the equipment operates for extended periods, consuming a lot of electricity and being environmentally unfriendly. Instant hot water dispensers have emerged to address this issue. They utilize thick-film heating technology, heating water quickly without the need for an inner tank. Water flowing through the thick-film tube heats room-temperature water to the desired temperature. However, in water dispensers, if certain components lack water, the heating elements can easily be damaged due to the lack of water. Therefore, application number 201920099466.X discloses a water shortage protection circuit for water dispensers, which includes an MCU and... A water flow sensor is installed in the water flow pipeline of the water dispenser. The positive input terminal of the sensor is connected to a voltage source VDD, and the negative input terminal of the water flow sensor is connected to the MCU through a resistor. The voltage source VDD is also connected to the negative input terminal through a resistor. The MCU is also connected to the power control switch of the heating element of the water dispenser. The MCU is also connected to a display screen. This device uses the water flow sensor to detect the water flow signal in the water flow pipeline and sends the detected water flow signal to the MCU for processing. When the water flow signal is interrupted or falls below a preset value, the MCU sends a corresponding control signal to the power control switch of the heating element, causing the heating element to be powered off and stop working, thereby effectively protecting the water dispenser.

[0003] The aforementioned patent discloses a water shortage protection circuit for water dispensers. It detects water flow signals through a water flow sensor and, when water shortage is detected, combines the MCU to cut off the power control switch of the heating element, thereby effectively protecting the water dispenser. However, it still has the following shortcomings in use: the water flow sensor detects water flow through a single water flow, which has limitations and poses a risk of false triggering, thus affecting the normal use of the water dispenser. In view of the above, this application proposes a water shortage protection circuit for water dispensers. Utility Model Content

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a water shortage protection circuit for water dispensers.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A water shortage protection circuit for a water dispenser includes a water flow sensor and a power control switch for a heating element. The water flow sensor is electrically connected to a signal conditioning circuit, the signal conditioning circuit is electrically connected to a water level detection electrode and a logic judgment module, the logic judgment module is electrically connected to a relay driver, and the relay driver is electrically connected to the power control switch for the heating element.

[0007] The logic judgment module includes a voltage conversion integration circuit and a dual-signal judgment circuit.

[0008] Preferably, the signal conditioning circuit includes comparators U1, U2, and U3. Pin 1 of comparator U1 is electrically connected to one end of resistor R1 and one end of resistor R3. Pin 2 of comparator U1 is electrically connected to one end of resistor R2 and one end of resistor R4. Pin 3 of comparator U1 is electrically connected to the other end of resistor R3. Pin 3 of comparator U1 is electrically connected to one end of resistor R5 and one end of resistor R6. One end of resistor R6 is electrically connected to the other end of resistor R3. The other end of resistor R5 is electrically connected to one end of resistor R7 and one end of capacitor C1. The other end of capacitor C1 is electrically connected to one end of resistor R8. The other end of resistor R7 is electrically connected to pin 2 of comparator U2. Pin 2 of comparator U2 is electrically connected to one end of capacitor C2. The other end is grounded. The other end of resistor R7 is electrically connected to one end of capacitor C2. The other end of resistor R6 is electrically connected to pin 1 of comparator U2. One end of capacitor C3 is electrically connected to pin 1 of comparator U2. The other end of capacitor C3 is electrically connected to the other end of resistor R8. One end of resistor R20 is electrically connected to pin 3 of comparator U2. The other end of resistor R20 is electrically connected to pin 1 of comparator U3. One end of resistor R10 is electrically connected to pin 3 of comparator U3. One end of resistor R9 is electrically connected to pin 2 of comparator U3. The other end of resistor R9 is grounded. One end of capacitor C4 is electrically connected to pin 2 of comparator U3. The other end of capacitor C4 is electrically connected to pin 3 of comparator U2.

[0009] Preferably, the voltage conversion integrator circuit includes operational amplifier U4 and operational amplifier U5. Pin 1 of operational amplifier U4 is electrically connected to one end of resistor R12 and one end of resistor R13. The other end of resistor R12 is grounded. Pins 3, 5, and 6 of operational amplifier U4 are all grounded. The other end of resistor R13 is electrically connected to pin 4 of operational amplifier U4. Pin 2 of operational amplifier U4 is electrically connected to one end of resistor R11 and one end of resistor R14. Pin 3 of comparator U3 is electrically connected to the other end of resistor R11. The other end of resistor R14 is electrically connected to pin 1 of operational amplifier U5. One end of capacitor C6 is electrically connected to pin 1 of operational amplifier U5. The other end of capacitor C6 is electrically connected to pin 2 of operational amplifier U5. Pins 5 and 4 of operational amplifier U5 are both grounded. One end of resistor R15 is electrically connected to pin 4 of operational amplifier U4. The other end of resistor R15 is electrically connected to one end of capacitor C5 and one end of resistor R16. The other end of resistor R16 is grounded. The other end of capacitor C5 is electrically connected to pin 3 of operational amplifier U5.

[0010] Preferably, the dual-signal judgment circuit includes a comparator U6. Pins 1 and 2 of the comparator U6 are electrically connected to the other end of resistor R15. Pin 3 of the comparator U6 is electrically connected to one end of resistor R17, one end of resistor R18, and one end of resistor R19. Pin 4 of the comparator U6 is electrically connected to the other end of resistor R17. The other end of resistor R19 is electrically connected to one end of capacitor C7. The other end of resistor R18 is electrically connected to one end of capacitor C6. The other ends of capacitor C7 and capacitor C6 are both electrically connected to the input terminal of the relay driver.

[0011] Preferably, the water flow sensor is a Hall effect flow meter, the output pulse frequency is proportional to the water flow velocity, the output is a constant high / low level when there is no water, and the output is a square wave pulse when there is water flow. The water level detection electrode is an AC excitation type dual electrode used to output an analog current signal.

[0012] Preferably, resistors R3 and R5 form negative feedback to control the gain, capacitor C1 is used for high-frequency filtering, comparator U1 is used for pre-amplification to pre-shape the input pulse, resistors R7, capacitor C2, resistors R8 and capacitor C3 form a second-order filter network to filter out motor interference, capacitor C3 and resistor R8 form phase compensation to prevent self-oscillation, comparator U3 is a hysteresis comparator to output a smooth DC voltage, and resistors R9 and R10 are used to set the hysteresis window to avoid false triggering caused by water flow fluctuations.

[0013] Preferably, the voltage conversion integration circuit integrates the signal over time using resistor R13, capacitor C5, and resistor R16 to reflect the voltage of the historical average flow rate. When there is a water shortage, comparator U6 outputs a high level, and the relay driver is energized to cut off the power control switch of the heating element.

[0014] Compared with existing technologies, the beneficial effects of this utility model are:

[0015] This invention determines the presence of water by simultaneously monitoring water flow and current conditions. The power supply is only disconnected when both conditions are met, effectively reducing the risk of false triggering and meeting usage requirements. Attached Figure Description

[0016] Figure 1 This utility model provides a connection block diagram for a water shortage protection circuit applied to a water dispenser.

[0017] Figure 2 This invention provides a circuit diagram of a signal conditioning circuit for use in a water shortage protection circuit of a water dispenser.

[0018] Figure 3 This invention provides a circuit diagram of a voltage conversion integration circuit for use in a water shortage protection circuit of a water dispenser.

[0019] Figure 4 This invention presents a circuit diagram of a dual-signal judgment circuit for use in a water shortage protection circuit of a water dispenser. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0021] Reference Figure 1-4 A water shortage protection circuit for a water dispenser includes a water flow sensor and a power control switch for a heating element. The water flow sensor is electrically connected to a signal conditioning circuit, which is electrically connected to a water level detection electrode and a logic judgment module. The logic judgment module is electrically connected to a relay driver, which is electrically connected to the power control switch for the heating element. The water flow sensor is a Hall effect flow meter, and its output pulse frequency is proportional to the water flow rate. It outputs a constant high / low level when there is no water and a square wave pulse when there is water flow. The water level detection electrode is an AC-excited dual-electrode type used to output an analog current signal.

[0022] The logic judgment module includes a voltage conversion integration circuit and a dual-signal judgment circuit;

[0023] The signal conditioning circuit includes comparators U1, U2, and U3. Pin 1 of comparator U1 is electrically connected to one end of resistor R1 and one end of resistor R3. Pin 2 of comparator U1 is electrically connected to one end of resistor R2 and one end of resistor R4. Pin 3 of comparator U1 is electrically connected to the other end of resistor R3. Pin 3 of comparator U1 is electrically connected to one end of resistor R5 and one end of resistor R6. One end of resistor R6 is electrically connected to the other end of resistor R3. The other end of resistor R5 is electrically connected to one end of resistor R7 and one end of capacitor C1. The other end of capacitor C1 is electrically connected to one end of resistor R8. The other end of resistor R7 is electrically connected to pin 2 of comparator U2. Pin 2 of comparator U2 is electrically connected to one end of capacitor C2. The other end of capacitor C2... The circuit is grounded. The other end of resistor R7 is electrically connected to one end of capacitor C2. The other end of resistor R6 is electrically connected to pin 1 of comparator U2. Pin 1 of comparator U2 is electrically connected to one end of capacitor C3. The other end of capacitor C3 is electrically connected to the other end of resistor R8. Pin 3 of comparator U2 is electrically connected to one end of resistor R20. The other end of resistor R20 is electrically connected to pin 1 of comparator U3. Pin 1 of comparator U3 is electrically connected to one end of resistor R10. The other end of resistor R10 is electrically connected to pin 3 of comparator U3. Pin 2 of comparator U3 is electrically connected to one end of resistor R9. The other end of resistor R9 is grounded. Pin 2 of comparator U3 is electrically connected to one end of capacitor C4. The other end of capacitor C4 is electrically connected to pin 3 of comparator U2.

[0024] Resistors R3 and R5 form negative feedback to control the gain, capacitor C1 is used for high-frequency filtering, comparator U1 is used for pre-amplification to pre-shape the input pulse, resistors R7, capacitor C2, resistors R8 and capacitor C3 form a second-order filter network to filter out motor interference, capacitor C3 and resistor R8 form phase compensation to prevent self-oscillation, comparator U3 is a hysteresis comparator to output a smooth DC voltage, and resistors R9 and R10 are used to set the hysteresis window to avoid false triggering caused by water flow fluctuations.

[0025] The voltage conversion integrator circuit includes operational amplifiers U4 and U5. Pin 1 of operational amplifier U4 is electrically connected to one end of resistor R12 and one end of resistor R13. The other end of resistor R12 is grounded. Pins 3, 5, and 6 of operational amplifier U4 are all grounded. The other end of resistor R13 is electrically connected to pin 4 of operational amplifier U4. Pin 2 of operational amplifier U4 is electrically connected to one end of resistor R11 and one end of resistor R14. Pin 3 of comparator U3 is electrically connected to the other end of resistor R11. The other end of pin 4 is electrically connected to pin 1 of operational amplifier U5. One end of capacitor C6 is electrically connected to pin 1 of operational amplifier U5. The other end of capacitor C6 is electrically connected to pin 2 of operational amplifier U5. Pins 5 and 4 of operational amplifier U5 are both grounded. One end of resistor R15 is electrically connected to pin 4 of operational amplifier U4. The other end of resistor R15 is electrically connected to one end of capacitor C5 and one end of resistor R16. The other end of resistor R16 is grounded. The other end of capacitor C5 is electrically connected to pin 3 of operational amplifier U5.

[0026] The voltage conversion integration circuit integrates the signal over time using resistor R13, capacitor C5, and resistor R16 to reflect the voltage of the historical average flow rate. When there is a water shortage, comparator U6 outputs a high level, and the relay driver is energized to cut off the power control switch of the heating element.

[0027] The dual-signal judgment circuit includes comparator U6. Pins 1 and 2 of comparator U6 are electrically connected to the other end of resistor R15. Pin 3 of comparator U6 is electrically connected to one end of resistor R17, one end of resistor R18, and one end of resistor R19. Pin 4 of comparator U6 is electrically connected to the other end of resistor R17. The other end of resistor R19 is electrically connected to one end of capacitor C7. The other end of resistor R18 is electrically connected to one end of capacitor C6. The other ends of capacitors C7 and C6 are both electrically connected to the input terminal of the relay driver. This invention determines the presence or absence of water by simultaneously monitoring the water flow status and current status. The power supply is only disconnected when both conditions are met, which effectively reduces the risk of false triggering and meets the usage requirements.

[0028] It should be noted that the relay driver can be a ULN2003 driver, which is an electrical component mainly used to control the on / off state of a relay coil, thereby indirectly controlling a high-power load (such as a heater). Its principle is as follows: when the MCU's GPIO outputs a high level (5V), the corresponding Darlington transistor inside the ULN2003 is turned on, and the collector (output terminal) is pulled down to a low level (close to 0V). One end of the relay coil is connected to the power supply (such as 12V), and the other end is connected to the output terminal of the ULN2003. Since the output terminal is pulled low, the coil forms a circuit, generating a magnetic field to attract the contacts. The normally open contact (NO) of the relay closes, and the high-power load (such as a heater) is powered on and works. When the MCU outputs a low level (0V), the ULN2003 driver is turned off, and the coil is de-energized. At this time, the back electromotive force generated by the coil is released through the built-in freewheeling diode. Its specific working principle is existing technology and will not be elaborated here.

[0029] Working principle: During use, the Hall effect flow meter monitors the water flow status in real time and outputs a pulse signal proportional to the flow velocity. The pulse signal is input to the signal conditioning circuit. Comparator U1 forms a negative feedback amplification through resistors R3 and R5 to amplify the weak pulse signal. At the same time, capacitor C1 removes high-frequency noise interference from the pulse signal. Then, the pulse signal enters a second-order bandpass filter composed of resistor R7, capacitor C2, resistor R8, and capacitor C3 to filter out low-frequency water pressure fluctuations and high-frequency motor interference. Then, comparator U3 outputs a smooth DC voltage with an amplitude positively correlated with the water flow frequency to avoid output jitter caused by water flow fluctuations. At the same time, the voltage conversion integrator circuit integrates the water flow signal voltage over time and outputs a voltage that reflects the historical average flow rate.

[0030] Simultaneously, the water level detection electrode detects the current. When there is water, the current is >50μA, and when there is no water, the current is <10μA. The current signal is also input to the signal conditioning circuit, which outputs a DC level.

[0031] Two DC currents are input to the dual-signal judgment circuit. Only when both conditions are met simultaneously will the comparator U6 output a high level, energizing the coil on the relay driver and cutting off the power control switch of the heating element, thus achieving the effect of protecting the water dispenser when there is a water shortage.

[0032] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A water shortage protection circuit for a water dispenser, comprising a water flow sensor and a power control switch for a heating element, characterized in that, The water flow sensor is electrically connected to a signal conditioning circuit, the signal conditioning circuit is electrically connected to a water level detection electrode and a logic judgment module, the logic judgment module is electrically connected to a relay driver, and the relay driver is electrically connected to a power control switch for the heating element. The logic judgment module includes a voltage conversion integration circuit and a dual-signal judgment circuit.

2. The water shortage protection circuit for a water dispenser according to claim 1, characterized in that, The signal conditioning circuit includes comparators U1, U2, and U3. Pin 1 of comparator U1 is electrically connected to one end of resistor R1 and one end of resistor R3. Pin 2 of comparator U1 is electrically connected to one end of resistor R2 and one end of resistor R4. Pin 3 of comparator U1 is electrically connected to the other end of resistor R3. Pin 3 of comparator U1 is electrically connected to one end of resistor R5 and one end of resistor R6. One end of resistor R6 is electrically connected to the other end of resistor R3. The other end of resistor R5 is electrically connected to one end of resistor R7 and one end of capacitor C1. The other end of capacitor C1 is electrically connected to one end of resistor R8. The other end of resistor R7 is electrically connected to pin 2 of comparator U2. Pin 2 of comparator U2 is electrically connected to one end of capacitor C2. The other end of capacitor C2... One end of the resistor is grounded. The other end of the resistor R7 is electrically connected to one end of the capacitor C2. The other end of the resistor R6 is electrically connected to pin 1 of the comparator U2. One end of the capacitor C3 is electrically connected to pin 1 of the comparator U2. The other end of the capacitor C3 is electrically connected to the other end of the resistor R8. One end of the resistor R20 is electrically connected to pin 3 of the comparator U2. The other end of the resistor R20 is electrically connected to pin 1 of the comparator U3. One end of the resistor R10 is electrically connected to pin 3 of the comparator U3. One end of the resistor R9 is electrically connected to pin 2 of the comparator U3. The other end of the resistor R9 is grounded. One end of the capacitor C4 is electrically connected to pin 2 of the comparator U3. The other end of the capacitor C4 is electrically connected to pin 3 of the comparator U2.

3. The water shortage protection circuit for a water dispenser according to claim 2, characterized in that, The voltage conversion integrator circuit includes operational amplifiers U4 and U5. Pin 1 of operational amplifier U4 is electrically connected to one end of resistor R12 and one end of resistor R13. The other end of resistor R12 is grounded. Pins 3, 5, and 6 of operational amplifier U4 are all grounded. The other end of resistor R13 is electrically connected to pin 4 of operational amplifier U4. Pin 2 of operational amplifier U4 is electrically connected to one end of resistor R11 and one end of resistor R14. Pin 3 of comparator U3 is electrically connected to the other end of resistor R11. The other end of 14 is electrically connected to pin 1 of operational amplifier U5. One end of capacitor C6 is electrically connected to pin 1 of operational amplifier U5. The other end of capacitor C6 is electrically connected to pin 2 of operational amplifier U5. Pins 5 and 4 of operational amplifier U5 are both grounded. One end of resistor R15 is electrically connected to pin 4 of operational amplifier U4. The other end of resistor R15 is electrically connected to one end of capacitor C5 and one end of resistor R16. The other end of resistor R16 is grounded. The other end of capacitor C5 is electrically connected to pin 3 of operational amplifier U5.

4. The water shortage protection circuit for a water dispenser according to claim 1, characterized in that, The dual-signal judgment circuit includes a comparator U6. Pins 1 and 2 of the comparator U6 are electrically connected to the other end of resistor R15. Pin 3 of the comparator U6 is electrically connected to one end of resistor R17, one end of resistor R18, and one end of resistor R19. Pin 4 of the comparator U6 is electrically connected to the other end of resistor R17. The other end of resistor R19 is electrically connected to one end of capacitor C7. The other end of resistor R18 is electrically connected to one end of capacitor C6. The other ends of capacitors C7 and C6 are both electrically connected to the input terminal of the relay driver.

5. A water shortage protection circuit for a water dispenser according to claim 1, characterized in that, The water flow sensor is a Hall effect flow meter, and the output pulse frequency is proportional to the water flow rate. When there is no water, it outputs a constant high / low level, and when there is water flow, it outputs a square wave pulse. The water level detection electrode is an AC-excited dual electrode used to output an analog current signal.

6. A water shortage protection circuit for a water dispenser according to claim 2, characterized in that, Resistors R3 and R5 form negative feedback to control the gain. Capacitor C1 is used for high-frequency filtering. Comparator U1 is used for pre-amplification to perform preliminary shaping of the input pulse. Resistors R7, capacitor C2, resistor R8, and capacitor C3 form a second-order filter network to filter out motor interference. Capacitor C3 and resistor R8 form phase compensation to prevent self-oscillation. Comparator U3 is a hysteresis comparator used to output a smooth DC voltage. Resistors R9 and R10 are used to set the hysteresis window to avoid false triggering caused by water flow fluctuations.

7. A water shortage protection circuit for a water dispenser according to claim 1, characterized in that, The voltage conversion integrator circuit integrates the signal over time using resistor R13, capacitor C5, and resistor R16 to reflect the voltage of the historical average flow rate. When there is a water shortage, comparator U6 outputs a high level, and the relay driver is energized to cut off the power control switch of the heating element.

Images